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How is that working out for you guys, the service switches at the indoor unit. I always thought that the disconnect was supposed to be between the main power line and the outdoor unit, since the outdoor unit feeds power to the indoor unit.

I heard that if you interrupt power between the two units you will get error messages when you turn the power back on, but if you kill power upstream from the outdoor unit, you will not have any problems.

You must break all three wires between the out door unit and indoor unit to meet code, if it applied in your area. There is a special 3 pole double throw switch that can be purchased for this requirement. I forget who makes them but they are easy to find.

One conductor is used as the info transmitter and that is where the error codes start..if that switch point is not solid. Also, the starting or disconnecting of the power to the unit and/or the inside switch should be done in a specific order in order to lessen the chance of getting an error code.

I beleive that all of the inside switches should be made before powering up the outside unit first.

"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis﻿ de Toqueville, 1835

Have found switching the control wire will cause problems over time, theres no current but the voltage ranges up and down to about 70v i think, from both the indoor and outdoor boards so it doesn't take much of a resistance to alter or stop the signal.

What we have done in the past is run power from the outdoor disconnect to a switch by the indoor unit and then back out to the outdoor unit, that way either switch will remove all power from the system and you are not switching the interconnecting wire which the systems were never designed to have happen.

Have found switching the control wire will cause problems over time, theres no current but the voltage ranges up and down to about 70v i think, from both the indoor and outdoor boards so it doesn't take much of a resistance to alter or stop the signal.

What we have done in the past is run power from the outdoor disconnect to a switch by the indoor unit and then back out to the outdoor unit, that way either switch will remove all power from the system and you are not switching the interconnecting wire which the systems were never designed to have happen.

The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

You must break all three wires between the out door unit and indoor unit to meet code, if it applied in your area. There is a special 3 pole double throw switch that can be purchased for this requirement. I forget who makes them but they are easy to find.

One conductor is used as the info transmitter and that is where the error codes start..if that switch point is not solid. Also, the starting or disconnecting of the power to the unit and/or the inside switch should be done in a specific order in order to lessen the chance of getting an error code.

I beleive that all of the inside switches should be made before powering up the outside unit first.

Code in most places is the switch must be visible from the fan unit, and within 50' of it. That pretty much makes it have to go inside the home. I read a post on an electrical site where the electrician would actually cover up the switch with sheetrock (Ha ha...!) Here's a cut-n-paste pic from the Mitsubishi Installation manual (with my comments added).
The Levitron switch is about $44 on Amazon.

This is what the electrician actually said... Click here for the web post

Another mactip of the day! Here is what I do when wiring mini split ac's during the rough in of a new house or addition. Either like I mentioned about running the feed thru the interior switch, or.... sometimes I just run 14-3 control cable in and out unspliced thru one of those adjustable depth single gang boxes that I normally use for granite countertop rough in to ensure the depth gets correct. Remember it is one continuous run of 14-3 in and out of the same switch box, with the proper length folded up inside the box. Next step, carefully mark the exact location of the box on your plans, how high and how many inches from the nearest corner. Next and best part- adjust the box so it doesn't stick out from the framing at all. leave a note for the drywall guy to leave it like that and bury over it with his wallboard. Trim out the house as usual, put a lockable disco on the outside at the compressor so a tag out, lock out can be performed and it will shut all power to the inside fan units. (good enough for me ) . At final, if the inspector throws a fit about where is the fan disco, blame the drywall guy and open up the wall where the switch box is. Say something derogatory about drywall hangers, and explain that if you only saw the box that they obviously buried, you never would have forgotten to install your thirty five dollar three pole switch to cut all lines to the 2 amp fan coil.........................